Experimental results on the nuclear structure of 44S and 26Si will be reported in this thesis. 44S is studied because of its interest in understanding how nuclei behave far from stability. 26Si is studied because of the impact of understanding its nuclear structure can have on the astrophysical 25Al(p,γ) reaction rate. These are two very differently motivated studies and will be described separately in Chapters 2 and 3, respectively. Chapter 2 focuses on the exotic N=28 nucleus, in 44S. Previous experiments observed a 4+ state and suggested that this state may exhibit a hindered E2-decay rate, inconsistent with being a member of the collective ground state band. We populate this state via a two-proton knockout reaction from a beam of exotic 46Ar projectiles delivered from the coupled cyclotron facility and measure its lifetime using the recoil distance method with the GRETINA γ ray spectrometer. The result, 76(14) stat (20) syst ps, implies a hindered transition of B(E2; 4+ →2+1 ) = 0.61(19) single- particle or Weisskopf units strength and supports the interpretation of the 4 + state as a K = 4 isomer, the first example of a high-K isomer in a nucleus of such low mass. Chapter 3 focuses on resonances above the proton threshold in 26Si. Previous experiments have solidified the placement of 3 resonances thought to contribute to the 25Al(p,γ)26Si reaction. A fourth resonance has been suggested by various experiments, but more recent experiments have suggested that this level has been misidentified. We populate excited states in 26Si via the 24Mg(3He,n) reaction at 10 MeV at the John Fox Lab at FSU. Neutron time-of-flight spectroscopy is used to identify which resonance is populated in 26Si and the γ-array at FSU is used to determine how these levels de-excite. The γ ray sensitivity in this experiment is the highest sensitivity reached to date, but a 4th resonance above the proton threshold was not identified, giving further indication that this state may have been misidentified by past experiments. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2017. / April 5, 2017. / Includes bibliographical references. / Ingo Wiedenhöver, Professor Directing Dissertation; Henry Fuelberg, University Representative; David Collins, Committee Member; Sam Tabor, Committee Member; Alexander Volya, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_507719 |
| Contributors | Parker, John J. (John Johnston) (authoraut), Wiedenhöver, Ingo (professor directing dissertation), Fuelberg, Henry E. (university representative), Collins, David C. (committee member), Tabor, Samuel Lynn (committee member), Volya, Alexander (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Physics (degree granting departmentdgg) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (111 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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